Vulcanization of rubber and production of vulcanized-rubber products.



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To all whom it may concern Be it known that we, Fnrrz HoFMAnN and f KURTGo'r'rwn, doctors of philosophy, chemists, citizensof the GermanEmplre,res1dtion of Rubber. and Production of Vulcanized-Rubber Products, ofwhich the following is; a specification.

In the applications, Serial Nos. 688761 and "6887 62, ;filed April. 5,1912, there are described-new caoutchouc substances and thevulcanization products thereof, which are obtained by treatment of theautopolymerization product of beta-gamma-dimethylerythrenewith basicsubstances and by subsequent vulcanization of the resulting prod In 'ourcompanion application Serial No. 795,506, filed October 16, 1913, wehave described that among these basic substances certain methylenebases, either open carbon solid and liquid derivatives of piperidin andits honiologues which have no odor and only a faint odor, lendthemselves excellently for the production of vulcanization products frompolymerized beta-gamma-di.- methylerythrene, and particularly from theautopolymerization product of this hydrocarbon.

' TVe have now discovered that the vulcanization of rubber-generally,either natural or synthetic, can be materially promoted by the use ofsuch a methylene base and particularly by the useof a piperidin base,etc.; and that by the use of such a base the vulcanization processproceeds more smoothly and more quickly while an improved product isobtained.. The present invention is accordingly generic in its nature tothe vulcanization of natural and synthetic rubbers.

According to the process of the present invention the rubber, eithernatural or synthetic, istreated either before or simulta- Ispecification of Letters IE'atent. I Pamemtgdl Jam, 2(3 1915 Applicationfiled October 16, ma. serial No. raaaoa. I

neously with the'addition or sulfur orof other vulcamzing agents with amethylene base and more specifically with a methylene base which is notfugitive at the temperature of vulcanization, and the base is thusIIICOIPOI'iLtBd within the mass and remains therein combined eitherphysically or chemically. Among such bases may be mentioned thesaturated aliphatic amine and their de-g rivatives (both open carbon andclosed carbon chain compounds) such astetramethylenediamin,pentamethylenediamin etc. which are saturated methylene open carbonchain bases, beta-beta-dimethyl-delta-methyltrimethyleneimin and itsurea derivatives, the urea and carbon bisulfidderivatives of such basesas dimethylamin, etc, the carbon blsulfid derivative of pyrrolidin(tetrahydropyrrol), and as particularly valuable bases there may bementioned piperidin (hexahydropyridin), its derivatives and homologues,etc., such as methylpiperidin, n-

thiopiperidin, benzaldipiperyl, pipiperidyh v dithiocarbamidate ofpiperidin, monopiperidyl ureavetc 'and in particular those solid andliquid derivatives of piperidin. and its holnologues which have no rior,or only a faint .odor;

The term methylene base is used as generic to those bases which aresaturated bases as distinguished from unsaturated bases such as anilinor pyridin', and which are not fugitive at the vulcanizationtemperature, and this term is intended to include as a genericterm-nonsfugitive open carbon chain bases and closed carbon chain iminobases such as piperidin, etc. lBy-the use of these bases, andparticularly by the use of piperidin the vulcanization not only proceedsmore quickly and more smoothly, but it is alsopossible to obtain eitheran improved vulcanized soft or hard rubber product.

-The rubber used in the present invention to' form the vulcanized hardor soft rubber product may beeither natural or synthetic, In certainrespects the synthetic rubbers difl'er from the natural rubber and thevulcanization problems presented are in many is kept at 120-125 C. (21atmospheres) for bers contain more or less of the dimeric hydrocarbonsor polymerization products produced at'the same time as the syntheticrubber, which are on the other hand absent in natural rubbers. Thevulcanization procnatural .rubberyand. of synthetic rubbersobtained bythe polymerization of rubberyi lding hydro-carbons, such as thebutadiene series among which there may be mentioned isoprene, erythrene,beta-gammadimethyl-butadiene etc.

The following examples further illustrate the novel rocess and theproduction of the novel pr ucts according to the present invention:-'

Example 1: 100 parts of Para-rubber are mixed with 10 parts of sulfurand 0.5 parts of piperidin and heated for 15 minutes to 135145 C. (3?;atmospheres). In this way a soft vulcanized product is obtained whichcontains 3.5 per cent. of combined sulfur. In the absence of piperidinthe'reaction requires about l-hour. If Para-rubber is substituted bysynthetic rubber, corresponding results are obtained.

Example 2: 100 arts of Para-rubber and 10 parts of fur and 1.5 parts ofpiperidin are heated at 120-125 C. (21:

' atmospheres) for 1 hour. A well vulcanized din era-rubber 'ves anu'nfinishe mass of little value un er the same conditions.

Example .3: 100 parts of erythrene caoutchouc, 10 parts of sulfur and 1part of piperidin are heated at 120125 C. (2% atmospheres) for 20minutes. A vulcanized erythrene caoutchouc is thus obtained.

Example 45-100 parts of beta-gamma dimethyl-butadiene rubber are heatedwith 10 parts of sulfur and 1 art of piperidin for 1 hour at 120125 C.2} atmospheres). The result is a good soft rubber substance.

Example 5: 100 parts of beta-gammadimethyl-butadiene rubber are heatedwith 40 parts of sulfur and 0.75 parts of iperidin to about 155 C. (5-6atmosp eres). After 2 hours a hard rubber product is obtained whichcontains about 25 combined sulfur. Without piperidin a product isobtained under the same conditions which contains only about 12 percent. of combined sulfur.

Example 6: 100 parts of Para-rubber, 10 parts of sulfur and-1 partofpip'eridyldithiocarbamidate of piperidin (melting at 172 C.) areheated for 15 minutes to 135- 145 C. (31} atmospheres). An execellentsoft rubber substance is obtained. A good product is also obtained ifthe temperature Froduct is obtained. Without iperi-- per cent. of

meanest about 1 hour. Similar or corresponding re sults are'obtainedwith synthetic rubbers or when other natural rubbers are employed.

Example 7: 100 parts of beta-gamma dimethyl-butadiene rubber, 50 partsof sulfur and 1 part of monc-piperidylurea or the formula:

CH -'CH: NHg-CO-Nr vc are heated to 155 C. for hours (5-6 atmospheres).An excellent hard rubber is obtained. If instead of 50 parts of sulfuronly 10 parts are used, and it is heated to 120125 C. (2% atmospheres)for 1 hour, a soft rubber product is obtained. Other synthetic ornatural caoutchoucs may be used in the above example; e. g. isoprenerubber, erythrene rubber, etc, also sodium butadiene rubber; also sodiumisoprene rubber, etc.

The piperidin compounds mentioned in the above examples can besubstituted by n-thiopiperidin (Michaeh's, Berichte 28, 1013) or bybenzalpipe'ryl (Journal f. prakt. C'hemz'e (2), Band 36, p. 130) or byother solid or liquid derivatives of piperidin or its homologues.

. Example 8: parts of Para-rubber, 10 parts ofsulfur, and lpart of theaddition product of dimethylamin and bisulfid of carbon are.heated for15 minutes to 130- 135 C. (3 atmospheres). A well vulcanized product isobtained. Without the above substance the reaction requires'over 1 hour.

Example .9: 100 parts of beta-gamma-dimethylbutadiene rubber, 10 partsof sulfur, and 1 art of tetramethylenediamin are heated or 1 hour to120-125 C. (2% atmospheres). A soft rubber substance is obtained.

Example 10: 100 parts of Para-rubber,

100 parts of beta-gamma-dimethylbuta be employed, or if the process iscontinued at the usual temperature and time of vulcanization, a largercombination of sulfur iseifected and a harder product is obtained. Theresults thus accomplished are much more marked than when other basessuch as pyridin, quinolin', dimethylanilin are present. These baseshardly possess the memes property of accelerating and improving thevulcanization. y

The vulcanized rubbers obtained according to the above examples containthe sulfur of vulcanization and a small amount of the added methylenebase, combined therewith,

- either physically or chemically or in part methylenebase, and heatingthe resulting product with a vulcanizing agent to effect vulcanization.I Y 3. The process of producing a vulcanized rubber which comprisesincorporating with rubber a small amount of a piperidin base. andheating the resulting product with a vulcanizing agent to effectvulcanization.

4. The process of producing a vulcanized rubber which comprisesincorporating with .rubber a small amount of piperidin, and

heating the'resulting product with a vulcanizing agent to effectvulcanization.

5. The processof producing a vulcanized natural rubber asmall amount ofa methylene base and heating the resulting product with a vulcanizingagent to efiect Vulcan;

ization.

6. The process of producing a vulcanized rubber which comprisesincorporating with natural rubber a small amount of a heterocyclicmethylene base, and heating the re sulting product with avulcanizing-agent to effect vulcanization.

a 7 The process of producing a vulcanized rubber which comprisesincorporating with natural rubber a small amount of a piperidin base,and heating the resulting product with a vulcanizing agent to eifectvulcanizatioxu 8. The process of producing a vulcanized rubber whichcomprises incorporating'with natural rubber a small amount of piperidin,

and heating the resulting product with a vulcanizing agent to efiectvulcanization.

9. As a new article of manufacture a vulcanized rubber combined beforevulcaniza- {)ion with a small amount of amethylene ase.

10. As a new "rticle of manufacture a I vulcanized rubber combinedbefore vulcanization with a small amount of a heterocyclic methylenebase.

11. As a new article of manufacture a vulcanized rubber combined beforevulcanization with a small amount of a piperidin base.

12.; As a new article of manufacture a vulcanized rubber combined beforevulcanization with a smallamoun't of piperidin.

13. As a new article of manufacture a vulcanized natural rubber combinedbefore vulcanization with a small amount of methylene base not fugitiveat the vulcanization.

temperature.

14. Asa new article of manufacture a vulcanized natural rubber combinedbefore vulcanization with a small amount of heterocyclic methylene base.rubber which comprises incorporating with .c'anization with a smallamount of piperidin.-

In testimony whereof we have hereunto of manufacture a vulset our handsin the presence of two subscribing witnesses.

FRITZ'HOFMANN. [n a] KURT GOTTLOB. [1a. a] Witnesses:

Hanan Norm, ALBERT Norm.

